As the Supreme Court mulls a Massachusetts law that limits protesters’ access to abortion clinic entrances, Professor David S. Cohen discussed the importance of buffer zones on Melissa Harris-Perry’s program on MSNBC on Jan. 18.

Buffer zones that require protesters to keep a specified distance from women’s health clinic entrances are critical to protecting patients and care providers from harassment and worse, Cohen said.

Doctors and other clinic workers and volunteers face threats on a daily basis, said Cohen, the co-author of a forthcoming book on violence against abortion providers that will be published by Oxford University Press.

Dangers have been keenly felt in Massachusetts, Cohen said, citing the deaths of clinic receptionists Shannon Lowney and Lee Ann Nichols, who were murdered in 1994 because they provided abortions.

“Buffer zones don’t cure the problem, but they provide a space,” Cohen said, observing that anti-abortion activist Paul Hill was able to shoot and kill a doctor by standing directly outside the clinic entrance.